JP2571499Y2 - Thread milling cutter with drill blade - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a thread milling machine with a drill blade provided with a drill hole for drilling a pilot hole at the tip of a thread milling machine for cutting a female screw.

[0002]

2. Description of the Related Art There is a thread milling tool as a tool for cutting an internal thread. This is provided with a thread cutting blade having a shape corresponding to a thread groove of a female screw to be formed on an outer peripheral portion, and is mounted on, for example, an NC milling machine or a machining center and is driven to rotate around an axis. A female screw is machined on the inner peripheral surface of the prepared hole by being relatively moved in the circumferential direction and the axial direction of the prepared hole in a state where a notch is formed in the prepared hole. Thread milling cutters are widely used. When cutting a female screw using such a threading milling cutter, it is necessary to pre-drill a pilot hole having a diameter slightly smaller than the inner diameter of the female screw to be formed as a pre-process, but a dedicated drilling tool is used. Since the method requires equipment and time for tool change, a threading milling machine with a drill blade, in which a drill blade for preparing a pre-drilled hole is integrally provided at the tip of the threading milling cutter, has recently been proposed. JP-A-63-200916 and JP-A-Hei 3
The tool described in Japanese Patent Publication No. 184722 is an example of such a case, in which a plurality of lands are provided with a torsion groove interposed therebetween. A drill blade having an outer diameter equal to or larger than the outer diameter of the thread cutting blade is provided at the distal end portion.

[0003]

However, in such a conventional thread milling machine with a drill blade, since the thread cutting blade and the drill blade are provided on one continuous land, the drilling performance and the thread cutting performance are simultaneously satisfied at a high level. It was difficult. In other words, it is necessary to secure a relatively large groove cross-sectional area in order to discharge chips at the time of drilling satisfactorily, and the number of lands is set to about two to three. The number of thread cutting blades is smaller than that of
There have been problems such as a reduction in machining speed and a shortened tool life. Generally, a multi-thread thread milling machine dedicated to thread cutting without a drill blade has a high rigidity so that an internal thread can be cut with high efficiency, so that 4 lands are used for a tool diameter of 8 to 16 mm, and 5 lands are used for a tool diameter of 16 to 25 mm. For 25 to 32 mm, about 6 lands are standard.

The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to efficiently cut an internal thread while preventing chip clogging at the time of preparing a prepared hole. .

[0005]

In order to achieve the above object, the present invention is directed to a thread milling machine for cutting a female screw on the inner peripheral surface of a pilot hole, and (a) at regular intervals around a rotation axis. (B) a plurality of main lands located across the provided plurality of main grooves; and (b) a plurality of main lands that are provided at axial end portions of the plurality of main lands. And (c) at least one sub-groove provided on each of the main lands, the sub-groove being parallel to the main groove and having a smaller groove width and a smaller groove depth than the main groove. (D) The outer diameter of each of the main lands formed by dividing the main land into a plurality of parts by the sub-grooves is twice or more than the main land formed by dividing the main land into a plurality of main lands. And multi-threaded cutting blade without lead Characterized in that it.

[0006]

[Function] Such a thread milling machine with a drill blade
First, a pilot hole is cut by a plurality of drill blades provided at the axial end portions of a plurality of main lands, and chips cut by the drill blades are preferably passed through a main groove having a large groove cross-sectional area. Since it is discharged, the pilot hole can be cut with high efficiency without causing chip clogging. Subsequently, a female screw is cut on the inner peripheral surface of the prepared hole by relatively moving a tool in a circumferential direction and an axial direction of the prepared hole in a state where a multi-threaded screw cutting blade is cut into the inner peripheral surface of the prepared hole. However, such a multi-threaded screw cutting blade has more than twice the number of main lands formed by dividing the main land into a plurality of main lands by sub-grooves having a smaller groove width and a smaller groove depth than the main groove. , Respectively, so 1
The amount of cutting per tooth is small, and the internal thread can be machined efficiently at a high feed rate and the tool life is improved. Further, since the groove cross-sectional area of the sub-groove is relatively small, sufficient tool rigidity is obtained, and there is no possibility that the dimensional accuracy of the female screw is impaired due to bending or the like.

On the other hand, the outer diameter of the second multi-threaded cutting edge provided facing the sub-groove is changed to the outer diameter of the first multi-threaded cutting edge provided facing the main groove. If the size is made smaller, the amount of chips at the time of cutting the female screw can be distributed according to the groove volume, and chips can be discharged well without chip clogging even if the groove volume of the sub-groove is small. In order to ensure a sufficient groove volume of the main groove, the above-mentioned thread milling machine with a drill blade usually has an interval from the first multi-thread cutting blade to the next second multi-thread cutting blade. Since the distance from the thread cutting blade to the next first multi-threaded cutting blade is smaller than the outer diameter of the first multi-threaded cutting blade, it is possible to reduce The cutting amount per tooth of the multi-thread screw cutting blade can be equalized.

[0008]

[Effect of the Invention] As described above, according to the thread cutting mill with a drill blade of the present invention, the female screw can be cut with high efficiency and high precision while preventing chip clogging at the time of preparing a pre-drilled hole. improves. Further, by making the outer diameter of the first multi-threaded cutting blade provided facing the main groove and the outer diameter of the second multi-threaded cutting blade provided facing the sub-groove different sizes, the female screw is cut. The amount of chips at the time of machining can be distributed in accordance with the groove volume, and the amount of cutting of each multi-thread screw cutting blade per blade can be equalized.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a view showing a thread milling machine 10 with a drill blade according to an embodiment of the present invention, wherein (a) is a front view seen from a direction perpendicular to an axis, and (b) is a top view. It is the bottom view seen. 2 and 3 correspond to FIG.
3A is a sectional view taken along line II-II and FIG. Such a thread milling cutter 10 with a drill blade is NC
A shank 12 gripped by a milling machine or the like and rotationally driven around an axis O, and a blade portion 14 for cutting a workpiece.
And a pair of main grooves 16 having a relatively large groove cross section twisted clockwise in this embodiment, that is, clockwise in this embodiment, are formed symmetrically with respect to the rotation axis O in the blade portion 14. As a result, a pair of main lands 18 that are spirally twisted are provided. Drill blades 20 for cutting a pilot hole prior to the cutting of the female screw are provided at the tip portions in the axial direction of the pair of main lands 18, respectively. These drill blades 20 each include a bottom blade 22 and an outer peripheral blade 24 provided continuously with the bottom blade 22.
And the tool center side ends of the pair of bottom blades 22 are connected to each other by thinning.

The pair of main lands 18 has the main groove 1
The sub-grooves 26 each having a smaller groove width and a shallower groove depth than the main groove 16 are provided in parallel with the main groove 16, and the main land 18 is divided into two by the sub-grooves 26. A total of four sub lands 28 are formed. The sub-groove 26 is formed at a substantially central portion of the main land 18,
The land widths of the sub lands 28 are substantially the same and are symmetrically positioned with respect to the rotation axis O. However, the spacing around the rotation axis O is improper due to the difference in the groove width between the main groove 16 and the sub groove 26. They are equally spaced. And those secondary lands 2
In FIG. 8, the multi-threaded cutting blades 30a and 30b which correspond to the thread groove shape of the internal thread to be formed and have an outer diameter substantially equal to the outer peripheral blade 24 of the drill blade 20 and have no lead are larger than the drill blade 20. It is provided on the shank 12 side in the axial direction. The multi-thread screw cutting blade 30a is provided facing the main groove 16 and corresponds to a first multi-thread screw cutting blade, while the multi-thread screw cutting blade 30b is provided facing the sub-groove 26. The distance from the multi-threaded cutting edge 30a to the next multi-threaded cutting edge 30b around the axis O is the distance from the multi-threaded cutting edge 30b to the next multi-threaded cutting edge 30a. Less than.

The thread milling cutter 10 with a drill blade configured as described above is mounted on, for example, an NC milling machine or a machining center, and is used for cutting an internal thread. By being sent in the axial direction relatively to the object, the drill blade 20 provided at the axial end portion of the main land 18 is provided.
Cuts the pilot hole. In this case, the chips cut by the pair of drill blades 20 are discharged well through the main groove 16 having a large groove cross-sectional area, so that the pilot hole can be cut with high efficiency without chip clogging. .

Subsequently, the multi-threaded cutting blades 30a, 30b are cut into the inner peripheral surface of the prepared hole, and are relatively moved in the circumferential direction and the axial direction of the prepared hole. To cut. In this case, the multi-threaded cutting blades 30a and 30b are provided on a total of four sub-lands 28 formed by dividing the main land 18 by the sub-grooves 26.
The number of cuts per tooth is smaller than when only a pair of multi-threaded screw cutting blades 30a are provided, in other words, compared to the case where only a pair of multi-threaded screw cutting blades 30a are provided. Tool life is improved. Also,
Since the groove cross-sectional area of the sub-groove 26 is relatively small, sufficient tool rigidity can be obtained, and there is no possibility that the dimensional accuracy of the female screw is impaired due to bending or the like.

As described above, according to the thread milling cutter 10 with a drill blade of the present embodiment, the female screw can be cut with high efficiency and high accuracy while preventing chip clogging at the time of preparing a prepared hole, and the tool life is extended. It will improve.

On the other hand, if the outer diameter of the multi-thread screw cutting blade 30b is smaller than the outer diameter of the multi-thread screw cutting blade 30a, the amount of chips at the time of cutting the female screw can be distributed in accordance with the groove volume. Even if the groove volume is small, chips can be discharged well without chip clogging. Also,
Conversely, the outer diameter of the multi-threaded screw cutting blade 30a is
If the outer diameter is smaller than b, the amount of cutting of each of the multi-threaded cutting blades 30a, 30b during cutting of the female screw can be equalized.

The above is merely a specific example of the present invention. For example, the number of the main lands 18 may be three or more, and the sub-grooves 26 for dividing the main lands 18 may be provided in the respective main lands 18.
The present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art, such as providing two or more.

[Brief description of the drawings]

FIG. 1 is a view showing a thread milling machine with a drill blade according to an embodiment of the present invention, wherein (a) is a front view and (b) is a bottom view.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG.

[Explanation of symbols]

 10: Thread milling cutter with drill blade 16: Main groove 18: Main land 20: Drill blade 26: Secondary groove 28: Secondary land 30a: Multi-thread screw cutting blade (first multi-thread screw cutting blade) 30b: Multi-thread screw cutting blade (second) Multi-thread thread cutting blade)

Claims (2)

(57) [Scope of request for utility model registration] 1. A thread milling machine for cutting a female screw into an inner peripheral surface of a pilot hole, comprising: a plurality of main lands positioned across a plurality of main grooves provided at equal intervals around a rotation axis; A plurality of drill blades are provided at the axial end portions of the plurality of main lands, respectively, for cutting the pilot hole prior to the cutting of the female screw, and the plurality of main grooves provided on the plurality of main lands, respectively. At least one sub-groove which is parallel and has a smaller groove width and a shallower groove depth than the main groove; and twice the main land formed by dividing the main land into a plurality by the sub-groove. A thread milling cutter with a drill blade, comprising: a plurality of thread cutting blades, each having an outer diameter equal to or less than the outer diameter of the drill blade and having no lead, respectively provided on the above-mentioned number of auxiliary lands. 2. An outer diameter of a first multi-threaded cutting blade provided facing the main groove and a second multi-threaded cutting blade provided facing the sub-groove among the plurality of multi-threaded cutting blades. The thread milling cutter with a drill blade according to claim 1, wherein outer diameters of the thread milling are different from each other.